to production of compounds, particularly acetaldehyde, that bind sulfite to
form α-hydroxysulfonates. 15 Indeed, S.
cerevisiae strains produce relatively high
levels of acetaldehyde. 16 However, the
study of production of sulfite-binding
compounds is beyond the scope of this
study.

Reduction of Brettanomyces and general
yeast populations using sulfur discs

The 6-week treatments were shownto be highly effective in decreasing both

Brettanomyces and general yeast populations (Tables 1 and 2, respectively) with
the exception of only one barrel that
presented reminiscent yeast populations
after the application of sulfur discs.

Three barrels of general yeast populations from the 3-week treatment had
reminiscent populations of yeast after
treatment. The reminiscent populations
of yeasts in some barrels after treatment
with sulfur discs can be attributed to an
incomplete burning of the sulfur discs,
since data showed that there were barrels with higher initial microbial loads
that had total elimination or undetectable levels of microorganisms, and
others that had fewer microorganisms
and did not have a total elimination.

No statistical differences were found
between the 3- and 6-week treatments
for both Brettanomyces and general yeast
populations, suggesting that the level
of disinfection was the same. SO2 rings
used and held for 3 or 6 weeks were sufficient to decrease the microbial loads
to undetectable levels in the majority of
the barrels. However, several variables
can influence treatment effectiveness
when microbial elimination is taken
into consideration, that is, the amount
of oxygen consumed inside the barrel,
the initial microbial load, the presence
of debris or residues of organic matter
and how much of the sulfur disc was
burned.

Conclusions

In this study, we considered the use
of a noninterfering matrix to be an important variable to prove the maximum
efficacy of SO2 whether in solution

inactivation are often contradictory. Some
authors refer its sensitivity to values higher
than 30 mg/L SO2, while others state it
should be regarded as resistant and growth
has been reported when values greater
than 30 mg/L SO2 are used. This controversy probably arises from differences in
experimental conditions and strain behavior variability. 14 Our results showed that

300 mg/L KMB was not sufficient to reduce the yeasts tested to undetectable levels. At pH 3.0, only strain CE78 (S. cerevisiae) was reduced 1.0 log10 unit, and at pHs

6 and 7). No significant differences were found for either strain when three different pHs were compared using either 0 or 300 mg/L KMB, since we observed that
KMB did not cause noticeable reductions in either strain. In fact, the effect of the
sanitizer was expected to be negligible for S. cerevisiae strains. In reality, S. cerevisiae
strains could be considered as controls since they are generally recognized as being
sulfite-resistant yeasts. For S. cerevisiae, differences in resistance have been attributed